Clear the existing identity if we are trying to register for notifications while in the simulator
Clear the existing identity if we are trying to register for notifications while in the simulator

Signed-off-by: Blake Skinner <f2809f73afc906ecbb5ce29ea24012b18700bcc7@mit.edu>

MIT-Mobile/MIT-Mobile-for-iOS,xNUTs/MIT-Mobile-for-iOS,xNUTs/MIT-Mobile-for-iOS,smartcop/MIT-Mobile-for-iOS,smartcop/MIT-Mobile-for-iOS,MIT-Mobile/MIT-Mobile-for-iOS